The instant invention relates to forming tools and more particularly to an improved forming tool which is operable in a turning operation for generating a predetermined configuration in a rotating metal workpiece.
The use of forming tools to generate various surface configurations in rotating metal workpieces has generally been known for many years. In this regard, a forming tool generally includes a blade or blade portion having a cutting edge which is formed in a prespecified configuration so that it is engageable with a rotating workpiece in order to generate a complimentary surface configuration in the workpiece. A forming tool of this type is generally mounted in a movable tool holding assembly so that the tool is movable toward and away from a rotating workpiece along an axis which is substantially perpendicular to the rotational axis of the workpiece. Accordingly, by moving the forming tool toward the workpiece with the tool holding assembly, the cutting edge of the forming tool is engageable with the workpiece in order to generate a configuration therein which is complimentary to that of the cutting edge.
The applicant's prior U.S. Pat. No. 4,174,916 which represents the closest prior art to the subject invention of which the applicant is aware, discloses a forming tool of the above-described general type comprising a tool body and a cutting blade or insert having a cutting edge thereon, wherein the cutting insert is removably mounted on the tool body, and a removable shim which is engageable with the insert to retain it in position on the tool body. In this regard, because the cutting insert is removable, it can be resharpened or replaced in the event that the cutting edge becomes worn or damaged rather than replacing the entire forming tool. However, it has been found that a forming tool of this type generally does not have a sufficient level of adjustability to enable it to compensate for variations in the thickness of the insert, such as caused by machining or grinding during resharpening.
The instant invention provides an improved forming tool of the type comprising a tool body and cutting insert on the tool body having a cutting edge thereon. More specifically, the forming tool of the instant invention comprises a tool body which is adapted to be received in a tool holder, the tool body having a substantially flat shelf formed thereon, a cutting insert having a cutting edge supported in a predetermined orientation on the shelf so that the cutting edge is engageable with a rotating workpiece, and a clamp assembly on the tool body for clamping the insert to retain it in the predetermined orientation on the shelf. The clamp assembly includes a clamp member having opposite first and second sides, and it includes spaced, substantially parallel, substantially straight elongated front and rear clamping pads on the first side thereof, the clamping pads being located adjacent the front and rear extremities of the clamp member. The clamp member has an arcuate crown formed on the second side thereof which is oriented so that the apex thereof is centrally located on the second side thereof in substantially parallel relation to the clamping pads on the first side of the clamp member. The clamp member is received and assembled in the forming tool so that the rear clamping pad is supported on the tool body and so that the front clamping pad is operable for applying clamping pressures to the insert in a direction toward the shelf in order to retain the insert in position on the tool body. The clamp assembly further includes at least one elongated threaded fastening element which is received in threaded engagement in the tool body and operative for urging the clamp member in a direction toward the insert. The fastening element has an enlarged head having an engagement surface on the underside thereof and it is oriented so that the engagement surface of the fastening element engages the crown on the clamp member along a line which is forward of the axis of the fastening element in order to urge the clamp member toward the insert. In this regard, because the engagement surface of the fastening element engages the crown of the clamp member along a line which is forward of the axis of the fastening element, the fastening element operates to rock the clamp member forwardly and downwardly so that the clamp member is pivoted toward the insert on the rear clamp pad in order to maximize the amount of clamping pressure applied to the insert by the clamp member. The clamp member is preferably supported exclusively on the clamp pads, and the clamp pads are preferably rounded slightly in their forward extents to enable the clamp member to more effectively pivot forwardly and downwardly as it is urged toward the insert. The tool body is preferably formed with a front face thereon and the shelf is preferably formed so that it extends rearwardly from the front face of the tool body. Further, the tool body preferably has a substantially straight rail formed thereon which defines the rear extremity of the shelf and engages the insert to further position it in the predetermined orientation on the shelf. The tool is preferably constructed so that when the insert is assembled on the tool body with the rear extremity thereof in engagement with the rail, the rail is substantially parallel to both the clamping pads and the crown on the clamp member. The forming tool preferably further includes a shim between the insert and the shelf and the insert is preferably supported on the shim on the shelf. Further, the insert is preferably formed so that the cutting edge thereof is substantially parallel to the clamping pads and the crown on the clamp member when the insert is assembled on the tool body. Still further, the tool preferably includes a pair of substantially parallel threaded fastening elements which are spaced along a line which is substantially parallel to both the crown and the front and rear clamping pads and operative for urging the clamp member toward the insert in the above-described manner. The forming tool also preferably includes a locator pin on the shelf adjacent to the rail, the locator pin having a lower portion of a first sectional dimension and an upper portion of a different second sectional dimension. The shim and the insert preferably have notches formed therein along the rear extremities thereof. The lower portion of the locator pin is preferably received in the notch in the shim and the upper portion of the locator pin is preferably received in the notch in the insert when the shim and the insert are assembled on the tool body. Further, the locator pin, the insert, the shim and the notches are preferably dimensioned so that they cooperate to prevent improper assembly of the insert on the tool body in a position wherein the insert is received between the shim and the shelf.
It has been found that the forming tool of the instant invention has specific advantages over the heretofore available forming tools. In particular, because of the manner in which the fastening element is operative for rocking or pivoting the clamp member forwardly and downwardly toward the insert, the clamp member is operative for applying increased clamping pressures to the insert. Further, because of this same feature, the clamp assembly has an increased level of adjustability to enable it to compensate for variations in insert thickness resulting from machining or grinding thereof during resharpening procedures. Further, because the front face and the rail on the tool body and the front and rear clamping pads and the crown on the clamping plate are preferably all substantially parallel, they more effectively cooperate to secure and retain the insert on the tool body by applying clamping pressures thereto with the clamping plate along a line which is substantially parallel to the cutting edge of the insert.
Accordingly, it is a primary object of the instant invention to provide a forming tool having a tool body, a removable cutting insert on the tool body, and a clamp assembly for clamping the insert in a predetermined position on the tool body, wherein the clamp assembly is adapted to compensate for variations in the thickness of the insert.
Another object of the instant invention is to provide a forming tool having a tool body, a removable cutting insert on the tool body, and a clamp assembly for clamping the insert on the tool body, wherein the clamp assembly is operable for applying increased clamping pressures to the insert.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.